The art of embedding an object in poured concrete by first forming a void in the concrete for receiving the object, and then securing the object in the void by some means, is old and well established. These voids are formed in a few different ways, such as by drilling a hole into concrete after the concrete has hardened, or by placing an insert of some kind into the concrete foundation before the concrete is poured and then removing the insert from the concrete once the concrete has hardened, thus leaving a void in the concrete. This art has applicability in several kinds of construction projects, from anchoring heavy machinery to a concrete foundation to building fencing.
Considering particularly the application of anchoring heavy machinery to a concrete foundation, it is customary in the art to form what are known as grout pits, a term meaning the filling of a void with grout, a concrete-like composition. After ascertaining the number and location of the voids that must be formed in order to properly anchor the machine in question, a number of inserts of some kind are placed into the desired positions and the concrete for forming the foundation is then poured. Once the concrete has hardened, the inserts are removed, thus forming voids in the concrete foundation. The machine is then secured by placing an anchor bolt from the machine into a void and then filling the void with grout, thus securing the anchor bolt in the proper location. Any other parts of the machine that need to be secured to the foundation are then secured in a similar manner.
Because a heavy machine creates a great deal of vibrational energy due to the relative motions of its respective parts, it is of the utmost importance that the machine be as securely anchored as possible. Experience has shown that, in order to produce an effective anchor, the grout pits must have a tapered shape, such that the bottom of the pit is wider than the top of the pit. Otherwise, the bond between the grout and the concrete foundation tends to deteriorate, and the quality of the product produced by the machine in question worsens, until eventually the machine may actually break away from the foundation, potentially causing injuries to the workers nearby as well as damage to both the machine itself and the building in which the machine is located.
At present, the inserts being used to form voids in concrete foundations are devices usually built by hand from conventional building materials, such as plywood. Such inserts are unsatisfactory for several reasons. Initially, there is the amount of time spent in constructing such inserts to the proper dimensions. Then there is the difficulty of removing such an insert from a void. This requires the use of hammers and other tools, and the stresses resulting from the removal of the devices may cause damage to the concrete foundation itself, which, to insure a proper installation, would require repeating the entire process. This, however is not usually done due to the time, labor and costs involved, the results being a poor installation of the machine due to an insecure mounting, and a resulting possibility of uncontrolled chatter or vibration marks in the finished parts. In addition, when it is desired to form grout pits along a line or at specified distances from one another, it is difficult to place these inserts in the proper locations, causing time delays and often causing slight errors in the placement of the inserts, thus weakening the effectiveness of the grout pits in anchoring the machine.
There are other types of devices at use in the art. An example of such a device is found in the Auciello et al. Patent, U.S. Pat. No. 4,515,271. This patent shows a tubular insert device with an internal line of scoring, allowing the separation of an upper and lower closure element by use of a holder tab. After a void in a concrete foundation is made, the device is removed by pulling on the holder tab, which lifts up the upper closure element and allows removal of the device. To facilitate packing and storing the devices, they are tapered such that the bottom of the device is wider than the top. In addition, FIG. 8 of the Auciello Patent shows the edges of the holder tabs serving as a measuring point to insure proper placement of the devices.